Patent Application
20180274464
The subject disclosure relates to the art of motor vehicles and, more particularly, to a lean NOx trap (LNT) regeneration system and method or regenerating a LNT.
Motor vehicles include various systems for reducing regulated exhaust constituents such as CO, NOx, and the like. One system, typically employed in diesel engine systems is a NOx absorber or Lean NOx trap (LNT). A NOx absorber typically employs an adsorbent, such as barium, that traps NO and NO2 molecules present in engine exhaust. Over time, the adsorbent may become saturated and further adsorption may be hindered. There exist a number of procedures for regenerating or desorbing NO and NO2 molecules from the adsorbent. The procedures are typically triggered when certain operating conditions of the LNT and the motor vehicle are met.
In most cases, a De-NOx event or regeneration is triggered based on engine working point parameters, such as engine speed and load, and LNT parameters such as LNT inlet temperature and NOx storage capability. Once a De-NOx event is activated, NO and NO2 molecules are released into the engine exhaust. The released NO and NO2 molecules react with hydrocarbons/CO/H2 to produce water and nitrogen. However, under certain conditions, CO2 may also be produced. Accordingly, it is desirable to provide a system for regenerating a LNT while lowering undesirable constituents, such as CO2.
In accordance with an exemplary embodiment, an emissions control system for a motor vehicle including an internal combustion engine includes a lean NOx trap (LNT) device including an LNT inlet and an LNT outlet, and a LNT sensor arranged at the LNT inlet. The LNT sensor is operable to detect a temperature of exhaust gases passing into the LNT device. A selective catalytic reduction (SCR) member is fluidically connected to the LNT device. The SCR device includes an SCR inlet and an SCR outlet. An SCR sensor is mounted to the SCR. The SCR sensor is operable to detect a temperature of the SCR. A LNT regeneration control system including a LNT regeneration controller is operatively connected to the LNT sensor and the SCR sensor. The LNT regeneration control system is operable to activate the LNT regeneration controller based on inputs from the LNT sensor and the SCR sensor.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the SCR includes an SCR substrate, the SCR sensor being operatively coupled to the SCR substrate.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include an engine load sensor operable to detect a load of the internal combustion engine, and a speed sensor operable to detect a speed of the internal combustion engine. The LNT regeneration control system is operable to activate the LNT regeneration control based on inputs from at least one of the engine load sensor and the speed sensor.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the LNT regeneration control system includes at least one memory module having stored thereon a SCR temperature threshold value, the LNT regeneration control system being operable to activate the LNT regeneration controller when the temperature of the SCR is below the SCR temperature threshold value.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the SCR inlet is fluidically connected to the LNT outlet.
In accordance with another aspect of an exemplary embodiment, a motor vehicle includes an internal combustion engine having an exhaust system, and an emissions control system fluidically connected to the exhaust system. The emissions control system includes a lean NOx trap (LNT) device having an LNT inlet and an LNT outlet. A LNT sensor is arranged at the LNT inlet. The LNT sensor is operable to detect a temperature of exhaust gases passing into the LNT device. A selective catalytic reduction (SCR) member is fluidically connected to the LNT device. The SCR device includes an SCR inlet and an SCR outlet. An SCR sensor is mounted to the SCR. The SCR sensor is operable to detect a temperature of the SCR. A LNT regeneration control system including a LNT regeneration controller is operatively connected to the LNT sensor and the SCR sensor. The LNT regeneration control system is operable to activate the LNT regeneration controller based on inputs from the LNT sensor and the SCR sensor.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the SCR includes an SCR substrate, the SCR sensor being operatively coupled to the SCR substrate.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include an engine load sensor operable to detect a load of the internal combustion engine, and a speed sensor operable to detect a speed of the internal combustion engine. The LNT regeneration control system is operable to activate the LNT regeneration control based on inputs from at least one of the engine load sensor and the speed sensor.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the LNT regeneration control system includes at least one memory module having stored thereon a SCR temperature threshold value, the LNT regeneration control system being operable to activate the LNT regeneration controller when the temperature of the SCR device is below the SCR temperature threshold value.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the SCR inlet is fluidically connected to the LNT outlet.
In accordance with yet another aspect of an exemplary embodiment, a method of regenerating a lean NOx trap (LNT) device of an internal combustion engine in a motor vehicle includes sensing a temperature of an SCR device fluidically connected to the LNT, sensing a temperature of the LNT device, and activating a regeneration controller to de-adsorb NOx from the LNT device based on the temperature of the SCR device and the temperature of the LNT.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein sensing the temperature of the SCR device includes sensing the temperature of an SCR substrate of the SCR device.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein sensing the temperature of the LNT device includes sensing a temperature of an LNT inlet of the LNT device.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include sensing a load on the internal combustion engine, and sensing a speed of the internal combustion engine, wherein the regeneration controller is activated based on at least one of the load of the internal combustion engine and the speed of the internal combustion engine.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the regeneration controller is activated when the temperature of the SCR device is below a predetermined temperature threshold.
The above features and advantages, and other features and advantages of the disclosure are readily apparent from the following detailed description when taken in connection with the accompanying drawings.
Other features, advantages and details appear, by way of example only, in the following detailed description, the detailed description referring to the drawings in which:
The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. As used herein, the term module refers to processing circuitry that may include an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory module that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.
A motor vehicle, in accordance with an aspect of an exemplary embodiment, is indicated generally at 10 in
As shown in
SCR device 50 is configured to reduce oxides of Nitrogen (“NOx”) in the exhaust gas. In various embodiments, SCR device 50 includes an SCR catalyst composition applied to substrate 60. SCR device 50 may utilize a reductant, such as ammonia (“NH3”), to reduce the NOx. More specifically, the SCR catalyst composition may contain a zeolite and one or more base metal components such as iron (Fe), cobalt (Co), copper (Cu) or vanadium (V) which operate to convert NOx constituents in the exhaust gas in the presence of NH3.
In accordance with an aspect of an exemplary embodiment, LNT device 48 includes at least one LNT sensor 64. LNT sensor 64 may take the form of a first temperature sensor 66 arranged at LNT inlet 54 to sense a temperature of exhaust gases entering LNT device 48. It is to be understood that the particular number, function, and location of LNT sensors may vary. SCR device 50 includes one or more SCR sensors 70. SCR sensor 70 may take the form of a second temperature sensor 72 arranged to detect a temperature of SCR substrate 60. It is to be understood that the particular number, function, and location of SCR sensors 70 may vary.
In further accordance with an exemplary aspect depicted in
In the exemplary embodiment shown LNT regeneration control system 80 is connected to first temperature sensor 66 arranged at LNT inlet 54 and second temperature sensor 72 arranged at SCR substrate 60. Additionally, LNT regeneration control system 80 is electrically connected to an engine load sensor 90 that may sense torque on internal combustion engine system 24 and a speed sensor 92 that may detect the speed of diesel engine 26.
As will be detailed more fully below, based on inputs from first temperature sensor 66 and second temperature sensor 72 as well as data that may be received from engine load sensor 90 and speed sensor 92, LNT regeneration controller 86 selectively activates a regeneration system 100 that is operable to selectively de-adsorb or purge LNT device 48 of NOx molecules. Regeneration system 100 may take on a variety forms.
Referencing
If the temperature at LNT inlet 54 is below the predetermined temperature threshold and/or the storage capability is above the predetermined storage threshold no action is taken and monitoring continues at block 204. If the temperature at LNT inlet 54 is below the predetermined temperature threshold and/or the storage capability is above the predetermined storage threshold, LNT regeneration controller 86 evaluates data from engine load sensor 90 and speed sensor 92 at block 220. If data from engine load sensor 90 and speed sensor 92 meets threshold criteria, LNT regeneration controller 86 activates regeneration system 100 to initiate a de-adsorption or NOx purge cycle for LNT device 48 at block 240.
It is to be understood that the exemplary embodiments describe a system for regenerating an LNT that is based not only on LNT parameters and engine parameters, but is also dependent upon SCR parameters. Further, LNT regeneration is targeted to periods when the SCR device is operating below threshold temperatures. Above the threshold temperature, the SCR device is operating at higher efficiency levels than when below the threshold temperature. Regeneration of the LNT creates heat that may be introduced into the SCR device to increase SCR substrate temperature above the threshold temperature. Thus, in accordance with the exemplary embodiment, regeneration of the LNT enhances operational efficacy of both the LNT and the SCR device in a single operation. Further, by tying LNT regeneration to SCR temperature, the number and of regeneration cycles may be reduced while at the same time enhancing regeneration efficiency.
The terms “about” and “substantially” are intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of ±8% or 5%, or 2% of a given value.
While the above disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from its scope. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiments disclosed, but will include all embodiments falling within the scope thereof.
